Web-type wooden truss with pressurized,adhesive joints



Jan. 20, 1970 A. L. TROUTNER 3,490,188

WEB'TYPE WOODEN TRUSS WITH PRESSURIZED, ADHESIVE JOINTS Filed Dec. 26,1967 A0 INVENTOR.

ARTHUR L. TROUTNER BY e4? ATTY.

United States Patent 3,490,188 WEB-TYPE WOODEN TRUSS WITH PRESSURIZED,

ADHESIVE JOINTS Arthur L. Troutner, 9777 Chinden Blvd., Boise, Idaho83700 Filed Dec. 26, 1967, Ser. No. 693,524 Int. Cl. E04c 3/42; E04b1/54 U.S. Cl. 52-644 6 Claims ABSTRACT OF THE DISCLOSURE This inventionrelates to web-type wooden trusses and to a no clamp method for theirfabrication.

Web-type wooden structural trusses comprising upper and lower chords andan interconnecting web member may be provided in two configurations,each of which has important applications. In one, which may be termed apanel beam, the web member is formed in a plurality of sections orinterconnecting members which are separated at spaced intervals bytransverse struts. In the other, known as a :bowstring truss, the upperchord is bowed and the web member comprises a plurality of sections orinterconnecting members arranged at spaced intervals and provided insufficient size, number and contour to carry the design load and impartto the truss the desired design appearance. In both cases theconventional construction technique requires gluing the componentstogether, using nails or clamps to hold pressure on the glue lines ofthe components while the glue sets.

It is the general purpose of the present invention to provide a methodfor fabricating web-type wooden trusses of the classes described abovewhich method may be effectuated rapidly, efficiently and without the useof nails or clamps to hold pressure on the glue lines during the gluingoperation.

It is another object of this invention to provide a method forfabricating web-type wooden trusses which leads to the production oftrusses of exceptional stability against shear, web-crippling andlateral chord rotation.

Still a further object of the invention is the provision of a method offabricating web-type wooden trusses which may-be applied to themanufacture of trusses having a variety of structural applications anddiverse design configurations.

The manner in which the foregoing and other objects of this inventionare accomplished will be apparent from the accompanying specificationand claims considered together with the drawings, wherein:

FIG. 1 is a fragmentary view in section illustrating a web componentemployed in the fabrication of the herein described truss,

FIGS. 2 and 3 are exploded and assembled views, respectively, of thetruss in one of its embodiments,

FIGS. 4 and 5 are transverse sectional views taken along lines 44 and5-5 of FIG. 3,

FIG. 6 is a view in side elevation of the truss of the invention in asecond embodiment,

FIG. 7 is an end view of the truss of FIG. 6,

3,490,188 Patented Jan. 20, 1970 FIG. 8 is a fragmentary view in sideelevation of the end portion of the truss in still another embodiment;and

FIG. 9 is an end elevation of the truss of FIG. 8.

The method of fabricating the presently described wood trusses takesadvantage of the fact that wood, when compressed, has a memory and seeksto return to its Origina configuration, particularly after having beenmoistened With water or a suitable solvent. Thus if the framingcomponents of the truss are grooved with tapered grooves, and themargins of the web components of the trussare compressed to providebeveled tongues of conforming contour, upon applying liquid glue to thetongues or grooves and assembling the components by wedging the tonguesinto the grooves, the liquid present in the glue will cause the tonguesto swell. This pressures the glue interfaces between the componentssufiiciently to interlock them while the glue sets, thereby eliminatingthe necessity of employing extraneous clamping fasteners or clamps.

The foregoing principle may be employed in the fabrication of thepaneled type trusses (panel beams) illustrated in FIGS. 1-5 inclusive.

Each of the trusses includes an upper chord 10, a lower chord 12 and aninterconnecting web or interconnecting member 14. It also may include aplurality of struts 16 which span the transverse intervals between thechords. In the truss of FIGS. 2 and 3 there are a plurality ofinterconnecting members disposed longitudinally of said chords, that is,one member 14 is positioned after another member 14 along thelongitudinal dimension of the chords. The interconnecting members 14 inthese figures are also disposed longitudinally at spaced intervals andthe struts 16 span said intervals,

Upper and lower chords, 10, 12 may comprise 2 x 4s or other suitablewooden structural members of the desired length. They are arrangedopposite each other and are provided with registering, inwardly taperedgrooves 18, 20 respectively. The grooves are formed in the opposed facesof the chords and preferably extend the entire length thereof.

Struts 16 likewise comprise 2 x 4s or other wooden structural componentsof suitable size and shape. They have a length equal to the distanceseparating the chords and preferably extend substantially at rightangles thereto. Their opposite side faces are grooved to form taperedgrooves 2.1, FIG. 5.

It is to be noted that struts 16 are multiple purpose members. They actas web splices and will transmit shear. They act as stiffeners againstweb crippling. Still further, they act as stabilizers of the chordmembers against rotation.

Webs or interconnecting members 14 comprise plywood, lumber orcomposition board panels characterized by the capacity for fibercompression along their various margins. Their size is such as to spanthe distance between the chords and the struts.

When manufactured, their side edges are square as indicated in brokenoutline in FIG. 1. However, to adapt them to the present purpose,selected margins are compressed by the application of dies of suitablecontour and angle. This forms wedge-shaped tongues 22 having an angleconforming to the angle of bevel of grooves 18, 20 in the chords andgrooves 21 in the struts. The angle of taper of the compressed tonguesis somewhat variable, depending upon the particular application, theidentity of the wood, the type of glue to be applied, the manufacturingprocedure to be applied. etc.

Since the side edges were square before compression, it will be apparentthat the tongues have been compressed more at their outer extremities(narrow portions) than inwardly thereof (wider portions). Therefore,when the tongues have been placed into the grooves and the tongues havebeen swelled by the liquid in the glue, there will be a greater wedgingpressure at the outer extremities of the tongues than inwardlytherefrom.

In general, however, the taper should provide a sufii cient degree ofwood compression so that the desired degree of swelling will occur uponapplication of the liquid glue. However, too great a taper should beavoided since this would result in overcompression with resultantcrushing of the wood fibers. It also would result in providing a tongueso blunt as to be unsuitable for use in assembling the trusses.

' As shown in FIG. 1, a satisfactory angle a of taper for the compressedtongues, as well as for the grooves in the chords and struts, lieswithin the range of from 2-30, preferably 5-15 with reference to theplane of the webs.

-The glues which may be employed in the practice of the present methodcomprise any liquid glues containing Water or a solvent which willactivate the memory of compressed wood. Particularly contemplated arethe aqueoils phenolic, urea, resorcinol, epoxy and casein glues employedin the woodworking industry.

' The glue is applied to either the compressed tongues or to the groovesin amount sufiicient to form glue interfaces 24, 25 between the webs andchords and glue interfaces between the webs and struts.

gThe construction of the bowstring type truss illustrated in FIGS. 6-9is similar.

1 The truss comprises an upper chord 30 which is bowed and a lower chord32 which is straight. The opposed faces of the chords are provided withtapered grooves in the manner previously described.

A plurality of Webs or interconnecting members 36, 38, 4t) interconnectthe chords at longitudinally spaced intervals. The upper and lowermargins of the webs are tapered by] compression to an angle of from2-30, preferably from 5-15", with reference to the plane of the webs,confogning in this angle to the angle of the grooves. Their uppermargins are sloped to conform to the contour of upper chord 30.

lieu of end web members 36, the uncompressed blocks 44 of FIGS. 8 and 9optionally may be employed.

'The webs are spaced non-continuously in sufficient size and number tocarry the design loads, thus facilitating construction and reducing theamount of material normally required.

The manner of assembly of either type of truss is shown schematically inFIG. 2. After the adhesive or glue has been applied, the components areplaced in proper relation to each other and pressed together in asuitable assembly jig. Immediately after it has been assembled, thetruss is removed from the jig and allowed to cure without the,application of additional pressure from clamps or mechanical fastenerssuch as nails. The swelling of the compressed wooden tongues, induced bythe application of the liquid component of the glue, pressures the glueinterfaces sufficiently to maintain pressure on the glue lines} pendingsetting of the glue. In this manner there is provided a truss of simpleconstruction which may be manufactured rapidly and inexpensively using aminimum of equipment and personnel. In addition, in its application thetruss has superior stability against shear, Web crippling and lateralchord rotation.

Itis to be understood that the forms of my invention herein shown anddescribed are to be taken as illustrative examples of the same and thatvarious changes in the shape, size and arrangement of parts may beresorted to without departing from the spirit of my invention or thescope of the subjoined claims.

Having thus described my invention, I claim:

1. A web-type wooden truss comprising a pair of spaced oppositelyarranged wooden chords having registering tapered straight grooves inthe opposed faces thereof,

(a) at least one straight wooden interconnecting member havingcompressed tongues on opposite margins, said tongues having a tapersubstantially conforming to the taper of the grooves in the chords,whereby a higher degree of compression occurs along the outerextremities than inwardly thereof,

(b) the tongues being wedgedly disposed into the grooves of the chordsand adhesively united thereto,

(c) the compressed tapered tongues, the wood memory and theadhesive-induced swelling imparting a wedging pressure between thetongues and the chords greater at the outer extremities of said tonguesthan inwardly therefrom.

2. A web-type wooden truss according to claim 1, wherein there are aplurality of interconnecting members disposed longitudinally of saidchords.

3. A web-type wooden truss according to claim 2, wherein saidinterconnecting members are disposed at longitudinally spaced intervals.

4. A web-type wooden truss according to claim 3, including a pluralityof struts interposed transversely between the chords in saidlongitudinally spaced intervals, said struts having straight taperedgrooves in their opposite faces, the edges of said interconnectingmembers facing said struts having compressed tongues having a tapersubstantially conforming to the taper of the grooves in the struts, saidtongues being wedgedly disposed into the grooves of said struts andadhesively united thereto, the wedging pressure between said tongues andsaid struts being greater at the outer extremities of said tongues thaninwardly therefrom.

5. The truss of claim 1 wherein the taper of the compressed tongues isfrom 230 with reference to the plane of the webs.

6. The truss of claim I wherein the taper of the compressed tongues isfrom 5-15 with reference to the plane of the webs.

References Cited UNITED STATES PATENTS 2,825,099 3/ 8- Simmons 52627917,433 4/ 1909 Hofheimer 1443 14 1,377,891 5/ 1921 Knight 527291,759,057 5/1930 Meem 52-729 2,263,198 11/1941 Valiton 144327 3,079,6493/ 1963 Willatts 52727 3,324,908 6/1967 Blanco 144-3 l3 FOREIGN PATENTS691,335 1964 Canada.

397,513 1933 Great Britain.

140,019 1953 Switzerland.

HENRY C. SUTHERLAND, Primary Examiner US. Cl. X,R,

